It's just that I was wondering if the jbl 305p mkii speakers will be more than i need to listen to to make music on Youtube sound excellent.
The JBL 305p mk2 is a very good speaker at a very good price (I assume you are looking at $200/pr).
It is hard to answer your question as you have it phrased, but you might go to your local Guitar Center (or whatever pro audio store is in your area) and see what they offer. Mackie and KRK also makes some great powered monitors and have competitive standing.
However, I don't see anyone getting the LSR 305P and saying "crap, I really screwed up", if that is your concern!
However, if you will only be listening to them at your desk and not cranking them, these model R1280T Edifiers will give you high quality sound for $100/pr!
Pros for Edifier:
Remote control
Same speaker with BT connection is available for an additional $30 (model R1280DB)
More compact
Woodgrain sides and
Controls (volume bass and treble) on side of speaker
Use RCA jacks
Less expensive
Pros for JBL 305:
More volume these can get loud!
Deeper bass (Edifier has 4" woofer)
Amazing projection into the room - you can sit anyplace in the room (well, be sane about it) and hear good sound - obviously not a factor if you are always seated at the desk, but if you lounge in your office or have friends in the room, this matters.
The extra expense of the JBL definitely gets a fundamentally more capable speaker, however, the Edifier may be all you need and offers good value if you appreciate the fact that it was designed more for the consumer market.
One thing to be aware of is that YouTube sound quality varys from decent to horrible. Getting better speakers may actually make poor recordings sound worse as you will hear distortion more clearly as well as the music. However, I would expect you experience the same with your headphones assuming they are decent. Headphones generally have the advantage for sound quality vs price over regular speakers - being able to position the speaker 1 to 1.5 inches from your ear eliminates a few of the issues speaker designers are normally confronted with.